In 1964, a military coup removed from office the democratically elected João Goulart. The plotters argued that Goulart’s affiliation to the labour movement represented a platform for a communist revolution. Rather, the coup was the outcome of a complex blend of internal, international and transnational inputs. At the internal level, there was the articulation of the economic elite’s interests, the spread of anti-communism among the armed forces and urban middle classes and the radicalization of social-economic demands. At the international level, the intensification of the Cold War in Latin America was shaping the US economic and geopolitical attentions towards Brazil particularly in the aftermath of the Cuban Revolution. After four years of democratic emulation, the authoritarian regime openly enforced a dictatorship. In response, part of the leftist opposition went underground, organising several different armed groups who shared the goal of enforcing the socialist revolution. Fractionated by ideological dissent, some groups were influenced by Guevara’s foquismo, while others embraced Maoists’ accounts on guerrilla warfare. There was also the development of the original ‘urban guerrilla doctrine’ designed by Carlos Marighella. In general, the guerrillas were active from 1968 to 1975, when state repression thwarted the last guerrilleiros, who were killed, imprisoned, or gone to exile. Thus, from the perspective of a neo-Gramscian political analysis, this chapter aims at presenting (1) an overview of the urban and rural guerrilla warfare in Brazil; (2) the specificities of the Brazilian repressive apparatus and the role of the US and the French counter-insurgency doctrines; (3) the international connections of the Brazilian guerrilla movements and (4) the guerrilla legacy for the Brazilian post-authoritarian era.